Method for preparation of trialkyl borates



ic 2,976,314 r. 1

United States Patent distillation during the course of the heating.Continued l i heating after the major portion of the acetone hadjbeerr2,976,314 removed resulted in a gradual increase in the reactiontem- IRperature. The final traces of the acetone and the initial} METHOD FOR EEg 0F TRIALKYL portion of the trimethyl borate distilled over between 54Carlos M. Bowman and Edward J. Watson, Midland,

Mich., assignors to The Dow Chemical Company, Midland, Mich., acorporation of Delaware No Drawing. Filed Mar. 2, 1959, Ser. No. 796,297

6 Claims. 01. 260-462) C. and 67 C. Then at 68 -70 'C., 195 grams (94percent of the theoretical yield) of trimethyl borate were distilled'and collected. a

The trimethyl borate thus prepared was 99 percent pure as confirmed byinfra-red analysis.

Example [I liter round-bottom fiask equipped similarly to that in Ex?ample I, and the mixture heated for one hour at. 54.-56 C. Theby-product acetone formed was removed from: the reaction flask bydistillation during the course of theheating. Continued heating afterthe 1118.101 portion of PWOTB the acetone had been removed resulted in agradual in-- R0 crease in the reaction temperature. The final traces ofThis separation procedure by the known methods is, in

most instances, both lengthy and troublesome. In the method of thepresent invention, however, trialkyl borates may be prepared by meanswhich obviate the separation of the desired product from azeotropicmixtures. A minithe acetone and the initial portionof the triethylborate distilled over between 70 C. and 115 C. Then at 117- 118 C., 180grams (75 percent of the theoretical yield) of Water-white triethylborate were distilled and collected. The triethyl borate thus preparedwas 95 percent pure as confirmed by infra-red analysis.

While the above examples describe specific starting compounds, otherstarting compounds may be employed, for example,

mum number of procedural steps are required and the ggigiifiggifiignedesired product is obtained in high yields and in a very zzdibutoxypmpane Y pure state.

The method of the present invention includes the reacting of boricoxide, B 0 with a 2,2-dialkoxypropane having the formula:

2,2-bis(2-methylpropoxy) propane; 2,2-dipentoxypropane;2,2-bis(3-methylbutoxy)propane; 2,2-dihexoxypropane;

2,2-bis(2-methylpentoxy)propane; OH3-C-OH3 4.0 2,2-diheptoxypropane;

R 2,2-bis(4-methylhexoxy) propane;

wherein R is a lower alkyl group containing from 1 to 8 carbon atoms,and heating the reaction mixture to a temperature between about 0 C. andabout 200 C., preferably at the boiling temperature of the reactionmixture, whereby a trialkyl borate may be produced. The reactionproceeds according to the equation:

2,2-bis 3 -ethylpentoxy) propane; 2,2-dioctoxypropane 2,2-bisS-propylpentoxy) propane; 2,2-bis 4-methylheptoxy) propane;

and the like may be employed, and analogous final prod; ucts obtainedtherefrom.

Various modifications may be made in the present "in vention withoutdeparting from the spirit or scope thereof,

and it is to be understood that we limit ourselves only as defined inthe appended claims.

We claim:

1. A method for preparing boron-containing esters comprising reacting,at a temperature of between about 0 C. and about 200 C. boric oxide witha compound having the formula:

and thereafter, a second fraction is distilled ofi. This OR secondfraction comprises a small portion of the desired product along with theremainder of the by-product. The R major portion of the desired productis thereafter distilled off and collected.

The following examples illustrate the invention but are not to beconstrued as limiting:

Example I 312 grams (3.0 moles) of 2,2-dimethoxypropane were mixed with70 grams (1.0 mole) of boric oxide in a 1- liter round-bottom flaskconnected to a distillation column wherein R is a lower alkyl radicalcontaining from 1 to 8 carbon atoms, and separating the resultingtrialkyl borate and equipped with a heating mantle, and the mixtureheated for one hour at 54 C.i2 C. The by-product CHa-CCH: acetone formedwas removed from the reaction flask by R "Patented Mar. 21', 19611.

8 carbon atoms, and separating the resulting trialkyl borate from thereaction mixture.

I 3. A method for preparing boron-containing esters comprising,reacting, at a temperature of between about C. and about 200 C. boricoxide with a compound having the formula: on.

CHr-C-CHa wherein R is a lower alkyl radical containing from 1 to 8carbon atoms, removing from the reaction mixture by distillation theby-products of the reaction and any unreacted starting materials, andseparating the trialkyl borate from the reaction mixture.

' 4. A method for preparing boron-containing esters comprising,reacting, at a temperature of between about 50 C. and about 150 C. boricoxide with a compound having the formula:

wherein R is a lower alkyl radical containing from 1 to 8 carbon atoms,removing from the reaction mixture by distillation the by-products ofthe reaction and any unreacted starting materials, and separating the.trialkyl borate from the reaction mixture.

5. A method for preparing trimethyl borate comprising, reacting, at atemperature of between about 0 C. and about C. boric oxide with acompound having the formula:

OCH:

CHr-C-CH:

O CH:

and separating the resulting trimethyl borate from the reaction mixture.

6. A method for preparing triethyl borate comprising, reacting, at atemperature of between about 50 C. and about C. boric oxide with acompound having the formula:

CHa--C-CH2 and separating the resulting triethyl borate from thereaction mixture.

.No references cited.

1. A METHOD FOR PREPARING BORAN-CONTAINING ESTERS COMPRISING REACTING,AT A TEMPERATURE OF BETWEEN ABOUT 0* C. AND ABOUT 200* C. BORIC OXIDEWITH A COMPOUND HAVING THE FORMULA: